Autonomous vehicles use various computing systems to aid in the transport of passengers from one location to another. Some autonomous vehicles may require an initial input or continuous input from an operator, such as a pilot, driver, or passenger. Other autonomous systems, for example autopilot systems, may be used only when the system has been engaged, which permits the operator to switch from a manual mode (where the operator exercises a high degree of control over the movement of the vehicle) to an autonomous mode (where the vehicle essentially drives itself) to modes that lie somewhere in between.
Such vehicles are typically equipped with various types of sensors in order to detect objects in the environment. For example, autonomous vehicles may include lasers, sonar, radar, cameras, and other devices which scan and record data from the vehicle's environment. Sensor data from one or more of these devices may be used to detect objects and their respective characteristics (position, shape, heading, speed, etc.).
A typical driver may communicate with pedestrians to express their intent in a number of different ways including make eye-contact, use hand gestures and other forms of communication. In this regard, a driver may let a pedestrian know that it is safe to cross the road. However, other than signaling devices typical to non-autonomous vehicles, such as turn signals, head lights, high beams, brake lights, reverse lights, and some audible signals (horns, reverse light beepers, etc.), autonomous vehicles lack the capability to directly communicate the vehicle's future behavior. In addition, while it may be sufficient for a driver to slow down or stop a vehicle at a cross walk in addition to making eye contact with, waving to, speaking to, or flashing lights to a pedestrian to communicate to the pedestrian that the driver will wait for the pedestrian to cross, simply stopping a vehicle without these driver-initiated signals may not be sufficiently reassuring to the pedestrian that it is indeed safe to cross.